Method of stricken-out character recognition in handwritten text

ABSTRACT

A method of stricken-out characters identification in a handwritten text recognition process, comprising parsing the scanned image into regions and objects, defining objects, containing handwritten characters, applying structural or feature classifiers for primary character recognition, applying one or more supplemental feature classifier, preliminarily trained by characters of strike-out, to identify a stricken-out character if any.  
     The stricken-out character may be further examined by special procedures, either automated or manual.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates generally to the optical character recognition and more particularly to the recognition of handwritten characters from bit-mapped image file.

[0003] 2. Prior Art

[0004] According to traditional methods of text recognition, a bit-mapped image of the scanned page is parsed into regions, presumed to contain images of characters with the further comparison of said images with the models from one or more special feature classifiers.

[0005] The very method is realized, for example, in U.S. Pat. No. 5680479 Oct. 21, 1997

[0006] The main drawback of the traditional approach is that the result of recognition of a stricken-out character is commonly not an error statement, but a mistakenly recognized symbol, likely thereto by contour. This causes recognition mistakes, since this character is not the one that has been stricken out.

[0007] Stated drawback reduce greatly the appliance of known method of text recognition. Known method is not suitable for attainment of the stated technical result.

[0008] Known methods do not provide to indicate a presence of a stricken-out character, thus causing recognition errors.

SUMMARY OF THE INVENTION

[0009] The main technical result of the present invention is in handwritten characters recognition improvement, anti noise protection of recognition process, providing a true identification of a stricken out characters.

[0010] The technical result is achieved by organizing of an additional specialized feature classifier within the system containing features of a bulk variety of characters of striking-out. In the case of high enough coincidence with the said classifiers element, the character is recognized as stricken-out and is directed for additional processing.

[0011] The utilization of the proposed method can greatly increase the recognition quality of handwritten characters, to make recognition more immune to noise.

BRIEF DESCRIPTION OF THE DRAWING

[0012] FIGURE is a block diagram showing the list of steps to be made on stricken-out handwritten characters recognition according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0013] The proposed method in addition to the prior art comprises a special means for overcoming the stricken-out character recognition errors. The said means comprises an additional feature classifier preliminarily trained by features of characters of strike-out.

[0014] The stricken-out character recognition process starts from primary applying structural or feature type classifiers to parsed images, presumably containing characters. In the case of primary recognition failure, multiple result of recognition or recognition with not high enough reliability level, the secondary attempt is performed along with one or more feature classifiers to recognize the character, narrow the list of possible characters versions or increase the reliability level of recognized character, respectively. In the case of primary or secondary recognition attempts success, one or more supplementary specialized classifiers are used, preliminarily trained by features of characters of strike-out.

[0015] In the case of close enough coincidence with the said additional classifiers model, the examined character is defined as stricken-out, and is directed to the additional processing. Said additional processing may be manual procedure containing human intervention, or a fully automated method.

[0016] The essence of the method is shown on the FIGURE.

[0017] The matter of the recognition is a graphic object, parsed from initial document bit-mapped image, containing stricken-out character.

[0018] The said graphic object is directed to one or more structural or feature type classifiers for primary recognition. This primary recognition in the present invention is the main character recognition means. As a result of the recognition process are one or more possible variants of characters along with corresponding reliability levels of each variant.

[0019] In a case of failure or multiple results of primary recognition the secondary recognition is then performed. A plurality of recognized variants of character are directed to one or more feature classifier for the secondary recognition and narrowing the possible characters (variants) list. The classifiers, used in the secondary recognition uses recognizing methods different from those used by the primary classifiers, thus the concurrent use of different types of classifiers additionally increases the total recognition quality.

[0020] After the examination in secondary classifiers, the number of possible variants of characters decreases greatly, typically to the only one, and their reliability increases.

[0021] After that the character is examined in one or more specialized feature classifier, preliminarily trained by characters of strike-out. After the special classifier examination, a decision can be made, whether to consider the character as stricken-out or assume the variant proposed by the primary or the secondary recognition. If the character is considered as stricken-out, it is directed then to additional processing. Said additional processing can be fully automated or can include the human intervention.

[0022] The method comprises at least the following steps. The graphic object (1), presumably containing stricken-out character, is directed for examination to one or more classifiers (7), assumed in the present invention as the primary recognition means. As a preferred embodiment in the present invention the primary recognition is performed by one or more structural classifiers (2). In a case of multiple results of primary recognition, the recognition results along with the graphic object (1) are sent for accurate definition to one or more classifiers (3) for secondary recognition, assumed in the present invention as the subsidiary recognition means.

[0023] After the primary or the secondary recognition the initial graphical object (1) along with the recognition version is examined in the supplemental specialized classifier (4) preliminarily trained by characters of strike-out.

[0024] In the case of high enough fitting the additional classifier (4), the character is considered as stricken-out. After that it is directed to additional processing (5) with further completing the recognition process (6). 

We claim:
 1. A method of stricken-out characters recognition in handwritten recognizing, comprising parsing of document scanned image into objects, determining among them objects, presumably containing handwritten characters, applying one or more classifiers for primary character recognition, selection of the most likely variant among a plurality thereof in a case of multiple recognition result on the previous step, applying one or more supplemental ad hoc feature classifiers of stricken-out characters, identification of the character as stricken-out in the case of fitting the stricken-out characters classifier with not lower then the preliminarily set reliability level.
 2. The method of stricken-out characters recognition as recited in claim 1, applying classifiers of structural type for primary character recognition.
 3. The method of stricken-out characters recognition as recited in claim 1, further applying an additional processing to the character, considered as stricken-out.
 4. The method of stricken-out characters recognition as recited in claim 3, where the additional processing further comprises use of human intervention. 